Fixed #14 : Back button not working in Slider Menu.

Author: opticod

source-code/app/src/main/java/org/buildmlearn/toolkit/activity/HomeActivity.java

@@ -82,7 +82,7 @@ public void onNavigationDrawerItemSelected(int position) {
             if (currentSection == null || selectedMenuItem != currentSection) {
                 currentSection = selectedMenuItem;
                 FragmentManager fm = getFragmentManager();
-                FragmentTransaction ft = fm.beginTransaction().setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
+                FragmentTransaction ft = fm.beginTransaction().setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE).addToBackStack(null);
                 Fragment f = fm.findFragmentById(R.id.container);
                 if (f != null) {
                     if (currentSection.isKeep()) {
@@ -111,6 +111,9 @@ public void onBackPressed() {
             mNavigationDrawerFragment.closeDrawer();
             return;
         }
+        if (getFragmentManager().getBackStackEntryCount() <= 1) {
+            finish();
+        }
         super.onBackPressed();
     }
 }